In general, an avascular necrosis of a femoral head refers to a disease in which a femoral head is dying off due to the block of blood flowing toward a femoral head. For many different causes, blood circulatory disturbance may occur in some or all regions of a femoral head. As a result, there appears to a progressive necrosis which destroys the femoral head and induces a secondary osteoarthritis.
Surgical treatment for an avascular necrosis of a femoral head are largely classified into a method of reviving an original joint and a method of replacing an original joint with an artificial joint. A femoral head drilling method or a core decompressing method is used as the method of reviving an original joint. In case of using these methods, a necrosis lesion of a femoral head is removed and then an operation for autogenous iliac bone graft and stem cell transplantation is carried out.
In this operation, a healthy spongy bone is removed from a hip joint bone of a patient. After getting rid of a dead bone of a femoral head, the spongy bone is transplanted by pressing the same against the femoral head. If it is not proper to use a patient's own iliac bone, a hip joint bone of other person is used. Use of a hip joint bone of other person poses a problem in that the post-operation physical adaptation period becomes longer. In case of transplanting a patient's own iliac bone, there is posed a problem in that the operation time grows longer and the pain felt by a patient after operation becomes acute.
As one example of instruments for the surgical operation of an avascular necrosis of a femoral head, there is known an instrument using a core decompression method, which includes: a center pin pressed against a necrosis lesion of a femoral head and formed into a needle-like rod structure having a specified diameter and a specified length; a core decompressor for performing a sawing operation by a predetermined distance from a femur surface to a necrosis lesion, the core decompressor having a middle portion guided by the center pin, the core decompressor attached to a drill hand piece at one end and provided with a cylindrical saw at the other end; a harvester inserted into a femur along a hole formed by the saw, the harvester configured to pick up a terminus portion of the sawed femur and to extract the terminus portion; and a pressing instrument for pressing the femur cell to enlarge the diameter thereof so that the femur cell extracted by the harvester can be re-entered into the hole and can be self-joined (see Korean Patent Application No. 10-2009-0128000 filed by the applicant of the subject application).
In the conventional instrument for the surgical operation of an avascular necrosis of a femoral head, a drill hole extending to a necrosis lesion is formed through the use of a drill. A center pin is inserted into the drill hole. Using the center pin as a guide, a decompressor is linearly moved forward. While repeatedly sawing a femur, the decompressor gains access to the necrosis lesion, thereby removing the necrosis lesion. However, the conventional instrument cannot remove a necrosis lesion larger in size than the outer diameter of the decompressor. For that reason, the conventional instrument suffers from a problem in that it is suitable for the removal operation of a narrow necrosis lesion but is not suitable for the removal operation of a wide necrosis lesion.